Bactericidal activity of diketene vapor

ABSTRACT

KILLING BACTERIAL SPORES AND BACTERIAL VEGETATIVE CELLS AT ROOM TEMPERATURE WITH VARYING DEGREES OF RELATIVE HUMIDITIES BY DIKETENE VAPOR.

3,733,413 BACTERICIDAL ACTIVITY OF DIKETENE VAPOR David R. Spiner and Robert K. Hoffman, Frederick, Md., assignors to the United States of America as represented by the Secretary of the Army No Drawing. Filed Dec. 29, 1967, Ser. No. 694,365 Int. Cl. A01n 9/28 U.S. Cl. 424-278 9 Claims ABSTRACT OF THE DISCLOSURE Killing bacterial spores and bacterial vegetative cells at room temperature with varying degrees of relative humidities by diketene vapor.

The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to us of any royalty thereon.

This invention relates to the killing of microorganisms and more particularly concerns an improved and effective bactericidal vapor.

The problem of disinfecting and sterilizing areas such as hospital operating rooms, patient wards, nursery rooms, and the like, along with their associated instruments, supplies, and equipment, has persisted, and continues to besiege mankind. Bacterial contamination is a constant threat, for example, in food processing plants, biological research laboratories, and even in the construction of sterile spacecraft for interplanetary biological exploration.

Heretofore, disinfectants were applied directly to those areas requiring sterilization. Large areas were expensive to treat, and generally, only the surfaces so treated were sterilized, the surrounding air not being affected. Perishable items and delicate laboratory instruments were subjected to the damaging effects of the disinfectants. Further, prior art disinfectants were generally less effective upon bacterial spores than bacterial vegetative cells.

In view thereof, an object of this invention is to provide an improved bactericide.

Another object of the invention is to provide such a bactericide which is lethal to both bacterial vegetative cells and bacterial spores.

Still another object of the invention is to provide such a bactericide as aforedescribed, which, in vapor form, will be capable of being rapidly disseminated and is efficiently penetratable to all areas of a confined space.

Other objects and advantages of the invention will become apparent as the invention is further described hereinafter.

Briefly, we have found that the foregoing objects may be attained by vaporizing diketene in a confined area.

More specifically, where diketene vapor is allowed to effuse, penetrate or evaporate into an area, the entire area, including the equipment and supplies confined therein, is efficiently and rapidly freed of harmful microorganisms.

Diketene is a colorless liquid at room temperature having a boiling point of 127 C. at 76 mm. of mercury pressure and a vapor pressure of 19 mm. of mercury pressure at 38 C. Diketene may be prepared by the spontaneous dimerization of ketene, a product obtained by the pyrolysis of acetone. It has the following structural formula:

United States Patent 3,733,413 Patented May 15, 1973 ice and must be stored from about 0 C. to 5 C. in order to retard polymerization.

The effectiveness of diketene vapor was evaluated in accordance with the following procedures:

EXAMPLE I Circular cotton cloth patches having an area of about 2 cm. are contaminated with an aqueous suspension of Staphylococcus aureus cells and allowed to dry at ambient temperature and relative humidity. ml. portions of diketene are placed on the bottom of l-liter bottles containing air of a predetermined relative humidity into which a contaminated patch containing about 645,000 Staphylococcus aureus cells is suspended about midway by a wire. After being exposed to the diketene vapor for 1 and 4 hours, the patches are placed in 10 ml. of an aqueous solution of 0.1% wt./vol. lecithin and 0.7% vol/vol. Tween 80, a non-ionic detergent comprising an emulsifier of polyoxyethylene derivatives of fatty acid partial esters of hexitol anhydrides, a product of Atlas Powder Company, and adjusted to pH 7 with 1 N sodium hydroxide solution. The organisms are dislodged by shaking thoroughly, whereupon serial dilutions are plated in enriched nutrient agar. The samples are incubated for 48 hours at 37 C. and the colonies resulting from the surviving microorganisms are counted. The percent organisms killed is calculated by comparing with the number obtained from an assay of unexposed contaminated cloth patches.

After being exposed to diketene vapor at room temperature for a period of 1 hour at relative humidity, of the cells were killed. At 50% relative humidity, room temperature, 50% of the cells were killed in one hour and in four hours 93% of the cells were killed.

EXAMPLE II The procedure outlined under Example I was repeated using cloth patches contaminated with approximately 380,000 Bacillus subtilis var. niger (Bacillus globigii) spores. After one hours exposure to diketene vapor at room temperature and 90% relative humidity, 100% of the spores were killed. At 50% relative humidity, room temperature, 27% of these spores were killed after one hours exposure, while 75% of the spores were killed after four hours exposure to the diketene vapor, room temperature.

It is apparent from the foregoing description that we have provided an improved vapor phase bactericide applicable to both bacterial vegetative cells and bacterial spores which is most effective at high relative humidities, and which is capable of rapidly penetrating all portions of confined areas when permitted to eifuse, suifuse or evaporate therein.

We claim:

1. A method for rapidly sterilizing a confined area contaminated with bacteria comprising exposing said area to an effective amount of diketene in the vapor phase.

2. The method according to claim 1 wherein said diketene vapor is employed in the presence of water vapor at a room temperature of about 20 to 30 C.

3. A method for rapidly inactivating and rendering nonviable bacterial spores and bacterial vegetative cells comprising exposing said spores and said cells to an effective amount of diketene in the vapor phase.

4. A method according to claim 3 wherein said cells 9. A method according to claim 7 wherein said bacteria are Staphylococcus aureus. are Bacillus globigii spores.

5. A method according to claim 3 wherein said spores are Bacillus subtilis var. niger. References Cited 6. A method of combating bacteria which comprises UNITED STATES PATENTS treating said bacterla with an effective amount of diketene in vapor phase. 3,238,096 3/1966 Kaye 424278 7. A method according to claim 6 wherein diketene is employed in the presence of water vapor. ALBERT MEYERS, Primary Examiner 8. A method according to claim 7 wherein said bacteria 10 M STEPHENS Assistant Examiner are Staphylococcus aureus cells. 

